This study investigated (a) the intraplant distribution of Euschistus heros (F.) (Hemiptera: Pentatomidae) in cotton, (b) its preference for different structures and areas of the cotton plant, and (c) the damage caused at different levels of infestation. Our results determined that, regardless of the time of day, E. heros adults significantly preferred the middle third of cotton plants in comparison to the upper and lower areas (F = 30.221; df = 2; P = 0.001). The adults were present on all cotton structures, and numbers were significantly higher on bolls and leaves/branches (F = 25.333; df = 5; P = 0.001) than on flower buds and flowers. In greenhouse tests, fiber yield, number of bolls per plant, and number of internal punctures in bolls responded significantly to increasing infestation levels of E. heros adults. Damage and yield reduction was observed at 1.5 to 2.0 adults/plant, indicating that an action threshold of 1 adult per plant should be adopted to avoid economic losses. Sampling during boll development should be by either whole-plant inspection or beat cloth methods between 0600 and 1800 h.